It is known practice to dye keratin fibres, and in particular human hair, with dye compositions containing oxidation dye precursors, which are generally known as “oxidation bases”, in particular ortho- or para-phenylenediamines, ortho- or para-aminophenols and heterocyclic bases.
Oxidation dye precursors are compounds that are initially uncoloured or sparingly coloured, which develop their dyeing power on the hair in the presence of oxidizing agents, leading to the formation of coloured compounds. The formation of these coloured compounds results either from an oxidative condensation of the “oxidation bases” with themselves, or from an oxidative condensation of the “oxidation bases” with coloration-modifying compounds, or “couplers”, which are generally present in the dye compositions used in oxidation dyeing and are represented more particularly by meta-phenylenediamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds.
The variety of molecules used, consisting on the one hand of the “oxidation bases” and on the other hand of the “couplers”, allows a very rich palette of colours to be obtained.
To localize the coloration product to application to the hair, so that it does not run onto the face or beyond the areas that are intended to be dyed, use has been made hitherto of conventional thickeners such as crosslinked polyacrylic acid, hydroxyethylcelluloses, waxes or alternatively mixtures of nonionic surfactants with a HLB (hydrophilic-lipophilic balance) that, when suitably selected, give rise to the gelling effect when they are diluted using water and/or surfactants.
It is also known that using anionic amphiphilic polymers in combination with oxidation dye precursor and oxidizing agent can obtain the hair dye compositions which do not run and thus remain better localized at the point of application.
However, the thickening systems mentioned above do not make it possible to obtain strong and chromatic shades with low selectivity and good fastness while at the same time ensuring good cosmetic condition of the treated hair. Moreover, the ready-to-use dye compositions containing oxidation dye precursor and also the thickening systems of the prior art do not allow a sufficiently precise application without running or drops in viscosity over time.
In some cases, the dyeing composition containing conventional thickeners along with the oxidation dye precursors exhibits before mixing with the oxidizing agents, a high viscosity. When mixed with the oxidizing agents, a homogeneous ready-to-use composition is difficult to obtain.
The aim of the invention is to provide a dyeing composition that does not run onto the face or out of the application area without impairing cosmetic and dyeing properties such as color intensity, selectivity and fastness with respect to chemical agents (shampooing, permanent-waving, etc.) or natural agents (light, perspiration, etc.), while at the same time giving the hair good cosmetic properties.
One of the aims of the present invention is to obtain a composition for dyeing the keratin fibers, especially the hair, with a low viscosity, however once mixing with a composition comprising oxidizing agent, the viscosity of the mixture immediately becomes sufficiently high for the mixture to be well localized on the hair, and at the same time conserving the dyeing properties obtained on the hair.